Consider Zero Grazing if Grazing is Not an Option
It comes as no surprise that the production costs of milk are directly related to the percentage of grass in the diet (Figure 1).
Obviously the data reported here is heavily influenced by production system and yield per cow, but the question is: can we make more use of grass in the intensive production system? You can begin by considering zero grazing (ZG) if grazing is not an option.
Grass benefits from the fact that its intake potential is higher than ensiled forages when done correctly.
To be done correctly zero grazed grass need to be harvested on a rotational basis identical to the grazing approach. It is worth remembering that ZG is not an excuse to harvest mature grass and ask the cows to eat it or expect to get a high level of performance out of it.
Dry matter intake is limited by forage NDF content. Compared to silage, cows will be able to consume 30% more NDF on fresh zero grazed grass. For example in Spring, cows can achieve 90% of their DMI grazing just 3 hours post morning and evening milking.
To maximise intakes when grazing high yielding dairy cows you would expect a reduced rate of DM utilisation.
With ZG you can expect to achieve exceptionally high rates of utilisation and produce more grass per hectare.
Another benefit of ZG is that forage and sward quality is maintained throughout the season without the negative effects of fouling of the sward by grazing cows and the build-up of rejected pasture. Typically ZG will increase grass production and utilisation by up to 30%.
Well manged grazing is obviously the cheapest method of getting grass into cows. However, if grazing management is poor ZG is cost effective and significantly cheaper than feeding grass silage to housed cows (Table 1). The most significant benefit of ZG however is from the additional milk from forage.
At best you would be looking to achieve 10-12 litres from grazed grass.
Zero grazed grass on the other hand would be able to achieve somewhere in the region of an additional 10 litres extra from forage. However, this will be considerably less if you make exceptionally good silage and do a very good job of grazing.
For a 100 cow herd over the ZG season, which can be as long as 210 days or more, you could be saving as much as 4kg of compound per day. With bought in feed valued at £190/t that would be a saving of around £16k per year for intensively managed high yielding dairy cows that do not usually make use of fresh forage.
On a million litres of production this would equate to a saving of 1.5ppl on bought in feed costs. Further savings would be achieved from lower production costs as a consequence of less DM losses both in the field and clamp compared to grass silage.
Table 1. Economics of Zero Grazing
|Lax Grazing||Good Grazing||Zero Grazing||3 cuts of silage|
|DM t Utilised/Ha (including loses)||6.50||8.00||10.50||9.90|
|Cost/t utilised (DM)||£143||£116||£143||£145|
|Feed out costs||£5.27||£4.57||£2.83||£21.20|
|Cost/t fed (DM)||£148.19||£120.70||£145.50||£166.15|
5 pointers to successful Zero Grazing
- Harvest what a good grassland based farmer would graze. ZG will not turn low D value grass into more milk.
- Monitor grass growth on the ZG platform, harvest at the right stage. Grass that gets too mature for grazing should be harvested immediately as silage or big baled to maintain quality, reduce waste, and return the sward to the rotation.
- Deliver the grass to the cows in an undamaged form. As soon as the grass is chopped or bruised it begins to deteriorate in nutritional quality. Unlike conserved forage it does not have the benefit of being pickled.
- Provide adequate feed space and be prepared to push up the forage several times. It is better to feed the grass on its own rather than incorporating into the TMR.
- Balance correctly. Grass is very high in protein, high in energy and low in fibre. ZG rations require some additional fibre and energy in order to utilise the protein better. Maize silage, Wholecrop, or a mix of NIS, Maize, and Sugar Beet is ideal. If feeding through the parlour consider a compound containing NIS to provide digestible fibre and buffering for the rumen.
Obviously ZG isn’t for everybody, however, hers with fragmented land area or higher yielding herds can most definitely benefit from ZG. The economics of ZG outlined in this article can be used to calculate the return on investment in the equipment or machinery required.
Implementing the 5 points above central for success on ZG.